CT Log Fetcher Timeout Handling

[cyrill-k]

The current CT Log fetcher does not deal gracefully with timeouts when requesting certificates. Instead the map server crashes if a timeout occurs.

Running updater for log https://ct.googleapis.com/logs/us1/argon2024 in range (1174372536, 1179006318, 1180131758) at 2024-03-15T17:02:49Z
Fetched 0 certs in 241.93 seconds at 2024-03-15T17:02:49Z
======== update finished at 2024-03-15T08:44:31Z

performing initial update: updating certs: updating next batch of x509 certificates: fetcher: Get "https://ct.googleapis.com/logs/us1/argon2024/ct/v1/get-entries?end=1174386871&start=1174386816": context deadline exceeded (Client.Timeout exceeded while awaiting headers)